Hydraulic pressure control means for automatic fluid speed change mechanism

ABSTRACT

An automatic control means in an automotive automatic speed change mechanism wherein a governor valve is so designed and arranged to generate a hydraulic governor pressure in relation to the revolutions per unit time of the driven shaft of said mechanism and in reversed relation to the throttle valve pressure which is delivered thereto from a throttle control valve.

United States Patent [72] Inventors HirojiYamaguchi;

Noboru Muraltami; Koiehiro Hirozawa, all 01 Kariya-shi, Aichi-ken, Japan1211 Appl. No. 828,895

[22) Filed May 29, 1969 [45] Patented July 6, 1971 73] Assignee AisinSelkl Company Limited Kariya-shi, Aichi-ken, Japan 32 Priority May31,1968 33] Japan [54] HYDRAULIC PRESSURE CONTROL MEANS FOR AUTOMATIC FLUIDSPEED CHANGE MECHANISM 3 Claims, 7 Drawing Figs.

[52] U.S.Cl 74/867,

74/752 [5 1] Int. Cl ..B60k 21/10,

[50] Field of Search 74/867, 868, 869, 763

[ 56] References Cited UNITED STATES PATENTS 2,697,363 12/1954 Sheppard74/868 2,740,304 4/1956 Sheppard 74/868 2,912,874 11/1959 Quistgaard etal. 74/869 3,321,056 5/1967 Winchell et a1. 74/869 X 3,425,300 2/1969Ohya et a1 74/763 Primary Examiner-Arthur T. McKeoln Attorney-Sughrue,Rothwell, Mion, Zinn & MacPeak ABSTRACT: An automatic control means inan automotive automatic speed change mechanism wherein a governor valveis so designed and arranged to generate a hydraulic governor pressure inrelation to the revolutions per unit time of the driven shaft of saidmechanism and in reversed relation to the throttle valve pressure whichis delivered thereto from a throt tle control valve.

PATENTEU JUL susm SHEET 1 OF 3 T ozimmo m FPQmIF 6 mwmomc $09 m om mm oPAIENTEB JUL 6 19m SHEET 2 OF 3 HYDRAULIC PRESSURE CONTROL MEANS FORAUTOMATIC'FLUID SPEED CHANGE MECHANISM This invention relates toimprovements in a relating to automatic fluid speed change mechanisms.It concerns especially with the hydraulic pressure control means forsaid speed change mechanisms. The fluid torque converter now broadly inuse as the automotive automatic speed change means if fitted furtherwith a mechanical speed change gearing so as to provide a plurality offorward speed change steps and a rear speed step, as is nowadays verycommonly known. In addition, the planetary gearing is most predominantlyemployed as the mechanical speed change gearing used in the above sensefrom the reason that it is highly convenient for its easy manipulation,its compactness and the like superiorities over other type machines.

In these conventional combined speed change arrangement, wherein themechanical gearing is controlled in its speed change operation byutilizing hydraulic pressure, one or a plu rality of hydraulic clutchesand one or a plurality of hydraulic brake means are selectively combinedwith each other and released and applied in a specifically selectedmanner. When, in this case, it is adopted to operate the mechanicalspeed change gearing in an automatic speed changing mode, shift valvemeans adapted for controlling the speed change is supplied, dependingupon the amount of the torque under being tiansmitted, on the one hand,and upon the occasional vehicle speed, with the throttle pressure whichvaries with the degree of opening of the conventional engine throttlevalve means, on the one hand, and the occasional governor pressure inproportion to the vehicle running speed, on the other hand, and indeed,in opposite relationship to each other. In effect, therefore, thedifferential between the both hydraulic pressures acts as thepredominant measure for attaining the desirous speed change.

With such conventional automatic speed change arrangements, the shiftvalve means must be increased in its number of values with the increaseof the number of speed change steps adopted, resulting in a highlycomplicated design of the hydraulic circuit for the realization of thedesired purpose.

The 'main object is to provide a hydraulic control means which iscapable of obviating the above mentioned conventional drawbacks.

In the control means embodying the principles of the invention, thethrottle pressure in relation to the degree of opening of conventionalengine throttle valve is applied in the same direction with the governorpressure in the above sense, for providing a governor pressure inreverse relationship with the degree of opening of the engine throttlevalve means, yet in relation to the occasional vehicle speed, saidgovernor pressure being conveyed to one or more ofshift valve means.

In this way, a simple and efficient control mechanism adapted for thedesired purpose may be provided so as to function depending upon theoccasional degree of throttle opening as well as the occasional vehiclespeed.

These and further objects, features and advantages of the invention willbecome more clear when read the following detailed description of theinvention by way of a preferred embodiment shown schematically in theaccompanying drawings which constitute a part of the presentspecification.

In the drawings FIG. I is a schematic illustration, substantiallysectional view of a representative arrangement of an automatic speedchange which is designed and arranged to cooperate with the hydrauliccontrol means of the present invention.

FIG. 2A and FIG. 2B constitute in combination a single drawing whichshows schematically-the hydraulic circuit em ployed in a preferredembodiment of the invention.

FIG. 3 is a chart wherein the throttle pressure has been plotted againstthe degree of opening of the engine throttle valve.

FIG. 4 is an explanatory chart showing the variation of governorpressure depending upon vehicle speed and engine throttle openingdegree.

FIG. 5 is a further explanatory chart showing the relationship betweenthe governor pressure and the speed change stage.

FIG. 6 is a still further explanatory chart showing the relationshipbetween the engine throttle opening degree and the vehicle speed.

Now referring to the accompanying drawings, a preferred embodiment ofthe invention will be described hereinbelow in detail. It should benoted, however, that same reference numerals are used throughout severalfigures and this specification for representing same or similar parts sofar as their respective functions are identical.

In FIG. 1 which shows only schematically an automatic speed changemechanism as employing a preferred embodiment of the hydraulic controlmeans according to this invention, the numeral 10 denotes an input shaftand 11 represents an output shaft; and there are provided twointermediate shafts l2 and 13 between the input and the output shafts,all these shafts being arranged substantially in a line as shown. Theinput shaft 10 is constituted in practice by the crankshaft of anautomotive internal combustion engine partially and schematically shownat 14. The output shaft 11 is mechanically connected through aconventional differential gearing and axle shaft, not shown, withautomotive drive wheels, as conventionally constructed, although thelatter are shown as only one at 15 for simplicity of the drawing.Intermediate shafts 12 and 13 are operatively connected with input shaft10 and output shaft 11, respectively, through suitable mechanical means,although not specifically shown only for its popularity.

The speed change mechanism shown comprises a fluid torque converter 16;hydraulically operated friction disc clutch means 17 and 18;hydraulically operated friction brake means 19 and 20; and a planetarygearing 21.

The hydraulic torque converter 16 comprises as conventionallyconstructed, a pump impeller 22; a turbine wheel 23 and a stator wheel24. Pump impeller 22 is rigidly connected through a drive plate 25 withthe engine crankshaft 10 and adapted for being driven therefrom. Turbinewheel 23 is mechanically coupled through a spline connection, not shown,with the first intermediate shaft 12. Stator wheel unit 24 ismechanically connected to an one way brake unit 26 which is shown onlyin a highly simplified manner. By the provision of said one way brake,the stator wheel 24 can rotate only in one direction which is same asthat of the pump impeller 22. The second shaft 12 is rigidly coupledwith. the clutch drum at 27 of first clutch unit 17 for rotation inunison with each other, said clutch drum being formed with an extensionacting as the inner hub of second clutch unit 18.

The inner hub at 142 of the first clutch unit 17 is splined with secondintermediate shaft 13 mounting nearly at its rear end a sun gear 31through spline connection and thus for unitary revolution with eachother. On the other hand, the clutch drum at 28 of second clutch unit 18is keyed to hollow sleeve 29 which mounts in turn a sun gear 30 througha spline coupling. Therefore, clutch drum 28, hollow sleeve 29 and sungear 30 rotate together.

Planetary gear 33 comprises gear elements 33a, 33b and 330 rigidlyunited with each other, yet having different respective numbers of gearteeth and being rotatably mounted on a carrier 36. This carrier 36 ismade integral with a brake drum 37 and mounts in turn rotatably aplanetary gear 32 which meshes through sun gear 30 with planetary gearelement 330.

Clutch drum 37 is fitted with one way brake 38 and rotatable in the samerotational direction with the engine crankshaft l0.

Planetary gear element 33b meshes with sun gear 31 and similar gearelement 33c does with sun gear 39 which is rigidly mounted on the outputshaft 11 for rotation therewith.

Numerals 19 and 20 represent separate band brake units which are shownin a highly simplified way only for convenience, said units beingarranged for bringing the respective clutch drums 28 and 37, and thussun gear 30 and carrier 36, respectively, into their rest conditions.

A manually controllable spool valve 102, shown in FIG. 28, has sixcontrol positions, or more specifically P-, R-, N-, D-, 2- andL-positions.

When the spool valve 102 is placed in the N-position, the speed changemechanism is brought into its neutral position. When the valve is placedin the L-position, a low speed drive ratio is generally obtained. Whenthe valve is manually shifted, however, from the high speed drive ratioto L-position, a middle speed drive ratio will be once realized and withthe wheel speed reduced to a certain limit, then the low speed driveratio will be attained finally.

With the valve 102 moved to its 2-position, either low speed drive ratioor middle speed drive ratio will be attained, de pending upon theoccasional wheel speed and the occasional opening degree of theconventional automotive throttle valve, not shown.

With the spool valve 102 adjusted to its D-position, there will be twodifferent operational modes of the speed change mechanism may beinvited. In this case, when the vehicle is started with low speed driveratio, the ratio may be adjusted automatically to the middle speed orthe high speed drive ratio, depending upon the occasional vehicle speed.Or conversely, when the vehicle speed drops, an automatic control oftransmission among low speed, middle speed and high speed depending uponthe occasional vehicle speed.

With the spool valve 102 moved to R-position, the reverse drive stagewill be realized.

With the spool valve 102 moved to P-position by means ofa selectionlever, not shown, pawl 211 is brought into meshing with an outer gear210 which is keyed to the output shaft 11 for fixing the latter againstrotation.

As will be understood from the foregoing, the forward low speed driveratio can be realized with the spool valve 102 adjusted to either one ofL-, 2- and D-position. With the spool valve positioned at D-position,any other speed ratio can not be realized, so far as the selection leveris not operated to other position. The low speed ratio can be realizedwith the spool valve positioned at L-position by applying hydraulicpressure to pistons 232 and 154 so as to actuate clutch unit 17 andbrake unit 20, respectively. The low speed drive ratio thus obtained areof two-way drive.

The low speed ratio is also realized with the spool valve adjusted toeither 2- or D-position, by applying hydraulic pressure to piston 140 toactuate clutch 17. In this case, the former function performed by brakeunit 20 is carried into effect by one-way brake 38. In this case, thelow speed drive is made in the mode of one-way drive.

In this case, one-way brake 38 acts as a kind of safety means. Now it isassumed that the vehicle is started with the spool valve 102 positionedat L, and then the latter is shifted to 2- or D-position. Then, thesecond brake unit 20 already applied for providing the low speed driveratio is disengaged, first brake unit 19 or second clutch unit 18 isdisengaged, and thus either the middle or high-speed drive ratio will beprovided. When there be a lag among these sequential operations, forinstance, when second brake unit 20 is released in advance of theactuation of the first brake unit or the second clutch unit, the engine14 will be subjected to a disadvantageous speed increase effectreversely through its crankshaft and a sudden and severe shock would beinvited at an succeeding engagement of the first brake or the secondclutch. In order to overcome this difficulty, one-way brake 38 takesover the function of second brake upon release thereof, and otherwisepossible engine speed increase in the above sense is positivelyprevented until the engagement of first brake 19 or second clutch 18will have been brought into effect. Thus, it will be clear that one-waybrake 38 acts during the low speed drive stage to prevent any reverserotation of carrier 36 relative to the regular rotational direction ofthe engine crankshaft 10, thereby taking over the function of secondbrake 20. Upon the engagement of first brake 19 or second clutch 18,carrier 36 will start to rotate in the same direction as the crankshaftl0 and one-way brake 38 will be disengaged automatically at a suitabletime, thereby providing a smooth change over from low speed drive ratioto middle or high-speed drive ration. With the low-speed drive ratio,rotation is transmitted from first intermediate shaft 12 through firstclutch unit 17 to second intermediate shaft 13, thereby the sun gear 31acting as the drive element of the gearing 21 being driven. Rotation isthus transmitted from the sun gear 31 to planetary gear elements 33b and330, thence to sun gear 39, thereby the output shaft 11 being driven ata reduced rate relative to second intermediate shaft 13. In this case,torque conversion will take place within the torque converter 16 and inthe gearing 21 so that the resulted driving torque at the output shaft11 depends upon the product of the both specific torque ratios at theconverter and the gearing. The intermediate speed drive ratio isattained in such a way that first clutch unit 17 is engaged. With theintermediate speed drive ratio thus attained, the power transmission isbrought about substantially in the same way as with the low speed driveratio. In this case, however, sun gear 30 is kept stationary by theapplication of first brake 19, this sun gear will act as the reactionmember in the gearing 21, in place of the carrier 36 in the foregoingstage. With the sun gear 31 rotating in this case in unison with bothintermediate shafts l2 and 13, and with the sun gear rotatablepermanently in unison with output shaft 11, the gear elements 33b and330 of the combined planetary gear 33 mesh respectively, while theremaining planetary gear element 33a meshes with plane tary gear 32mounted on the carrier 36 and kept in meshing with sun gear 30, saidcarrier acting as such for said planetary gear 33. Since, at the presentstage, the sun gear 30 is kept stationary by the application of firstbrake 19, the carrier 36 rotates in the forward rotational direction. Inthis way, the sun gear 39 and thus the output shaft 11 is driven at acertain reduced rate relative to the second intermediate shaft 13 whichratio is smaller than the low speed drive ratio.

The intermediate speed drive ratio is obtained in the following twoways: In the first instance, the spool valve 102 is adjusted to either2- or D-position and the vehicle speed is selected within a certainrange by manipulating the conventional throttle valve, not shown. In theinstance, the spool valve is adjusted from the high-speed drive ratio toL-position. With the spool valve positioned at any one of L-, 2- and D-positions, the low-speed drive ratio will be realized when the vehiclespeed drops beyond a certain predetermined value. With the spool valvepositioned at 2- or D-position, the intermediate speed drive ratio willbe realized when the vehicle speed increases beyond a certain value. Onthe contrary, when the spindle valve 102 is being kept at L-position, aspeed change to either the middle or high-speed drive ratio can not berealized.

The high speed drive ratio can be realized by manipulating the spoolvalve 102 to D-position with the vehicle speed kept at a reasonably highvalue. In this case, first clutch 17 is engaged, first brake 10 orsecond brake 20 is released and second clutch 18 is engaged, the latterbeing actuated by applying hydraulic pressure upon its actuating piston235, as will be described more in detail hereinafter.

With this high-speed drive ratio attained, first intermediate shaft 12drives the sun gear 31 through the intermediary of first clutch unit 17,as in the similar way with the case of the low speed or the intermediatedrive ratio attained. Second clutch l8 acts to connect first clutch drum27 which is coupled with first intermediate shaft 12, through secondclutch drum 28 to sun gear 30. In this way, both sun gears 30 and 31 aredriven in unison with each other from first intermediate shaft 12 andthe planetary gearing 21 is driven as a rigid unit, said firstintermediate shaft and said output shaft being coupled directly ineffect with each other.

With the high-speed drive ratio thus attained, the torque converter 16may be said to act only as a kind of fluid coupling, thus practically adirect drive being established between input shaft 10 and output shaft11.

The reverse drive stage can be established by bringing second clutch 18into engagement along with second brake 20. In this case, power istransmitted from the input shaft through torque converter 16, firstintermediate shaft 12, second clutch l8, sun gear 30, planetary gear 32,gear ele ments 33a and 33c of combined gear 33, and sun gear 39, to theoutput shaft 11. By the application of second brake 20, planetary gearcarrier 36 acts as the reaction member of the gearing 21. in this casethe reaction force of the carrier 36 is directed in the forward drivedirection. Since there are two planetary gears 32 and 3.3 between thedriving and driven sun gears 30 and 39, the sun gear 39 and the outputshaft ill are driven in the reverse drive direction with a certainreduction rate relative to the first intermediate shaft 12-. Under theseoperating conditions, torque converter 16 functions generally in thetorque increasing way, and thus the torque implied upon the output shaftis defined by the product between the torque increasing factor atconverter 16 and that provided by the planetary gearing 21.

Under the neutral condition of the speed change mechanism as realized bymoving the manually operatable valve 102 to N-position, clutches 1'7 and18 and brakes 19 and 20 are all kept in their released position. F orthe application of first brake unit 19, hydraulic pressure is fed toworking chamber 236 so as to actuate piston 1511, thereby rod 153 beingurged to move in its working direction for the applica tion of brakeband 30. There is a brake releasing chamber 239 in opposition to thehydraulic working chamber 236, said chamber 239 housing therein a returnspring 152 which acts to return the piston i151 for releasing the brake19 when hydraulic pressure is supplied to the releasing chamber 239 inopposition to that prevailing in the working chamber 236.

For the application of second brake 20, hydraulic pressure is suppliedto working chamber 237 for actuating piston 154 which is then urged tomove against the action of return spring 155 and in the direction forthe application of brake band 41.

From the foregoing, the speed change mechanism in which the hydrauliccontrol means embodying the principle according to this invention aswill be described hereinafter is fitted can be understood in its generalconstruction and operation.

The hydraulic control mechanism according to this invention comprisesgenerally a pump means 100, said manually operatable valve 102, ahydraulic pressure regulating valve 103, a throttle adjuster valve 104,a 1-2 position selector valve 105, a 2-3 position selector valve 107, aspeed adjuster valve 113. Pump means 100 is of a constant delivery type,preferably one having an impeller gear and an internal tooth gearmeshing therewith. Pump means 100 is so designed and arranged that itsucks oil from reservoir 59 through a filter 6b and a suction piping 61,and delivers it under pressure to a discharge piping 62. As shownschematically in FIG. 1, pump means 101! is so arranged that it isdriven from the input shaft 10 through pump impeller 22 of torqueconverter in. From the discharge piping 62, a piping 66 branches off andis arranged to act as line pressure conduit for providing hydraulicpressure to several friction clutch units as well as brake units whichhave been described hereinbefore by reference to FIG. 1, as will becomemore clear as the description proceeds.

Regulating valve 103 shown in FIG. 2A acts to regulate the hydraulicpressure in the piping 66. This valve W3 is made into a spool valvehaving separated lands 54a and 54b and urged by a return spring 117 tomove downwards in FIG. 2. The valve spool of the pressure regulator 103is slidably housed in its valve casing 103a which is formed with severalports at 158, 160, i161 and 162. Ports 161 and 162 are hydraulicallyconnected with the line pressure conduit 66, the latter port E62 beingso through the intermediary of a reduced flow passage or orificeschematically shown at I159. Port 158 is hydraulically connected with aconduit 65 which is connected I in turn to the suction piping til ofpump means 10ft. Port 166 is formed with an orifice 170, onlyschematically shown, thence through a conduit $3 to the torque converter16. By selecting the orifice 179 to a proper size, the hydraulicpressure supplied to the converter in can be determined at a proper one.

Governor-type valve 113 shown in FIGS. 1 and 2 develops a hydraulicpressure depending upon the occasional vehicle speed, which hydraulicpressure is utilized for automatically selecting suitable one of thevarious speed drive ratios of the speed change mechanism, as will bemore specifically described hereinafter. This governor valve 113comprises a casing 243 fixedly mounted on the output shaft 11, a valvemember 251 which is slidably mounted within the interior space of saidcasing 243, an inner weight mass 246, an outer weight mass 245 and atension spring 248 arranged between said weight masses 24 5 and me.These weight masses and the valve member are arranged at both sidesrelative to the output shaft illl. These weight masses and the valvemember 251 are limited in their outwardly movable ranges by theprovision of a traversely extending rod 249 relative to the output shaftand substantially passing through the governor valve assembly R13, andstop means 250 and 252 which are fixedly, yet detachably mounted at theboth extremities of said rod 249'. The valve member 251 is formed withthree lands 251a, 2511; and 25llc which have differentpressure-receiving areas from each other. The governor valve casing 243is formed with ports 253, 254 and 255 of which the second port 254 ishydraulically connected to oil reservoir 59, although the piping servingfor this purpose has been omitted from the drawing for simplicity. Port253 is connected through a piping 71 to the line pressure conduit 65which is formed therein with an orifice at 256 shown only schematically,Port 255 is connected to a piping 73 and its respective branch pipings73a and 73b with ports 118$ and 187 of the throttle valve assembly 104for introducing reduced hydraulic pressure delivered therefrom.

Throttle valve 164; appearing in FIG. 2B in the form of a spool valve isdesigned and arranged to provide a variable hydraulic pressure inresponse to occasional position of a conventional automotive acceleratorpedal 34, for the adjustment of the shift point of the speed changemechanism, and for the control of the hydraulic pressure to be suppliedto various clutch units and brake units which have been alreadydescribed by reference to FIG. 1. The throttle valve 104 is controlledthrough a dov/nshift valve 35 which comprises a valve member 118 and aport 180, the latter acting as a discharge one. Valve member 118 isarranged to be operated by means ofa suitable mechanical link mechanism,not shown, from the accelerator pedal 36 in such a way that with theaccelerator is moved in the throttle opening direction, the valve member118 is moved rightwards in FIG. 2B. As commonly known and thus not shownspecifically, the accelerator pedal is mechanically connected through asuitable linkage, not shown, with the carburetor for the vehicle driveengine 14.

The throttle valve 104 comprises a spool valve member 120 provided withlands .1200, 12012 and 120C, on the one hand, and several ports such asat 18d, 185, 1%, 187 and 189. A spring 129 is inserted under compressionbetween said two valve members 118 and 120. A further spring 121 isprovided at the right-hand side of valve member 120 in opposition tosaid spring 3119. Ports 284i and 189 serve for discharge service, whileport 1% is connected through a conduit 67 to the line pressure piping66. Port 187 is formed with an orifice 188, only schematically shown,and connected through conduits 73a and "73b with port 185. Conduits 73aand 73b are connected hydraulically with piping 73 which is connected inturn hydraulically with port 255 of said governor valve 113.

2-3 shift valve i0? is provided with a spool valve member 129 and aspring 128 for urging resiliently the latter in the upward direction inMG. 2A and formed with a smallest land 32%, two smaller lands 1129c and129d and a largest land 12%. The valve 107 is further provided withports 217, 218, 220, 222 and 2,23 and two chambers 2'06 and 219.Although the connecting means are not shown for simplicity, ports 217and 218 serve for conducting hydraulic liquid from the valve to oilreservoir 59. Chamber 2H9 serves no other purpose than the better andeasier cutting of the valve bore. Port 220 is connected through aconduit 83 to port 172 of the manual shift valve M12. Port 222 isconnected through conduit 34 and branch piping 84a to the workingchamber 234 of second clutch unit 18, on the one hand, and throughbranch piping 84b to the releasing chamber 239 of first brake unit 19,on the other hand. Port 223 is connected through conduit 79 to port 178of manual shift valve 102.

l-2 shift valve 105 serves for control the vehicle speed between thefirst speed stage and the second speed stage and operates in such a waythat when the first brake unit 19 is actuated, the second brake unit 20is released, and vice versa. The valve 105 has a valve member 123 whichis formed with smallest land 1230, two middle sized lands 123!) and 1230and largest land 123d. In order to urge resiliently the valve member 123upwards in FIG. 2A, there is provided a spring 214 between the smallestland 123a and the stationary valve casing at 105a. The valve 105 isformed with ports 193, 199, 201, 202, 203, 204 and 205, and withchambers 194, 200 and 206. Ports 199 and 203 are hydraulically connectedwith oil reservoir 59, although the connecting means are not shown forsimplicity,and serve for discharging oil from the valve. Port 193 isconnected through conduit 77 to port 176 of the valve 102. Port 205leads through conduit 78 to port 177 of the valve 102. Chamber 200 hasno other purpose than more convenient and easy mechanical working ofthevalve bore.

Port 201 is connected through conduits 72b and 72 to port 173 of thevalve 102. Conduit 72 is connected hydraulically with conduit 72a whichis connected in turn hydraulically with the actuating chamber at 231 offirst clutch unit 17. Port 202 is connected through conduit 81 to port207 of the actuating chamber 236 of the first brake unit. Port 204 isconnected through conduit 80 to port 240 of the actuating chamber 237 ofsecond brake unit 20.

The operation of the hydraulic adjusting valve arrangement is asfollows:

The oil pressure regulating valve 103 serves for the regulation of thehydraulic line pressure to a predetermined max imum pressure prevailingin the piping 66 and various piping means which are kept incommunication therewith, for every working condition of the speed changemechanism, as well as the hydraulic pressure regulator mechanism.

When the valve 103 operates to regulate the pressure of the dischargedhydraulic fluid from pump means 100, the lower surface of land 54a avalve member 5 3 cooperates to a larger or lesser degree with the uppersurface of the ring wall 208 in the valve casing 1030, for performingthe pressure regulating service. A reduced hydraulic pressure relativeto the line pressure upon flowing from port 160 through the orifice 170is conveyed further through conduit 63 to the torque converter 16. Aconduit 64 connects the converter 16 with a check valve 111 the outletof which leads through port 212 to a lubricating circuit, not shown.Check valve 111 serves for keeping the hydraulic pressure prevailingwithin the torque converter substantially at a predetermined constantvalue. A spring 138 is provided for resiliently urging the ball at 139of the check valve 11 1 in the valve closing direction so as to cut offthe port 212.

Governor valve 113 delivers the hydraulic governor pressure which isvariable and applied to the valve member 251, said variable governorpressure being a function of the rotational speed of output shaft 11which affects the relative position of the inner and outer weight massesand the tension of the spring 248 provided therebetween. With everyoperational mode of the mechanism, the hydraulic pressure delivered frompumping means 100 is conveyed through orifice 256 and conduits 66 and 71to the port 253 ofgovemor valve 113. The valve casing 243 of thegovernor 113 rotates with the output shaft 1 1 and with lower vehiclespeed a certain hydraulic pressure, which is determined by thedifference between the centrifugal forces acting upon the inner weightmass 246, on the one hand, and the outer weight mass 245 and the valvemember 251, on the other hand, and by the throttle pressure as appliedupon the differential area between lands 251b and 2510 of the valvemember 251, will be applied upon the differential area between bothvalve lands 251a and 251b. This hydraulic pressure will increase, withspeed increase at the vehicle drive wheels 15.

With higher vehicle speed, the outer weight mass 245 will shift outwardsunder the action of the increased centrifugal force and finally bebrought into abutting engagement with the snap ring 24 8 acting as astop. Under these operating-conditions, the hydraulic pressure appliedupon the valve member 251 will be counterbalanced by the centrifugalforce acting upon the inner weight mass 246, the spring force at 248which has been increased by virtue of said outward displacement of theouter weight mass 245 and finally the aforementioned throttle pressure.Under these conditions, the centrifugal force induced in both weightmasses will vary in a two-step course and relative to the vehicle speedas well as the throttle pressure, as will be easily seen from FIG. 4.Actuation of the accelerator pedal 34 will be transmitted through thevalve member 118 of the valve 35 upon the valve member 120, thusbringing the throttle pressure to be conveyed to conduit 73. Thishydraulic pressure is generally lower than the line pressure, and willvary from nearly zero value which is attained by closure of saidthrottle, to that as high as the line pressure which is realized uponopening of said throttle. The line pressure will be applied from theconduit 67 into the throttle valve 104, a variable hydraulic pressureshown in FIG. 3 appearing at both sides of the valve land 120a, theright-hand side chamber only being denoted by the numeral 191. Thisvariable hydraulic pressure is conveyed through port 185 to the throttlepressure conduit 73, thence to port 255 of governor valve 113.

The overall operation modes of the speed change mechanism are asfollows:

NEUTRAL RANGE When the vehicle driver manipulates a selector lever, notshown, which is mounted in the neighborhood of the driver's seat, so asto bring the manual shift valve 102 to its N-position which is theneutral position, the hydraulic line pressure supplied from conduit 66through ports 174 and 175 will be checked by valve lands 114b and 1140,thus no hydraulic pres sure being transmitted to other valve means andseveral hydraulically actuating piston means for friction clutches andbrakes, and thus the speed change mechanism is kept at its neutralpiston.

L-RANGE When the selection lever is manipulated to adjust the manualshift lever 102 to L-position, the line pressure prevailing in theconduit 66 will be conveyed through the port 175 situated between valvelands 1144b and 114C in the drawing, to valve ports 176 and 177. Theline pressure is then conveyed through port 174 and the valve spacebetween the lands 1140 and 114d to port 173. The hydraulic pressure isconveyed from port 177 through conduit 78 to port 205. On the otherhand, the line pressure will be conveyed through conduit 77 and port 193to the chamber 194. The combined pressure appearing at this stage in thechamber 194 by the hydraulic pressure and the spring 214 will act uponthe valve 123 upwards in the drawing to L-position where the latter iskept fixed at the low speed position. By this shift movement of valve123, port 205 is brought into communication with port 204, the hydraulicline pressure being thus conveyed through conduit 80 to the actuatingchamber 237 of second brake unit 20. At the same time, line pressurewill conveyed from port 173 through conduits 72 and 72a to the actuatingchamber 231 of first clutch unit 17. On the other hand, line pressureconveyed through conduits 72 and 72a to port 201 is interrupted by thevalve lands 123a and 123b, thus the pressure being confined within achamber shown at 200. Line pressure will emerge from the conduit 67through port 186 at the throttle valve 1%, appearing at the right-handchamber 191 of valve land 120a, at the left-hand chamber thereof. Then,the hydraulic pressure is conveyed from port to the throttle pressureconduit 73, thence to port 255 of the governor valve 113.

1n this way, the first clutch unit 17 and the second brake unit 20 arebrought into actuation, thus the planetary gear carrier 36 being broughtinto its stationary position. Therefore, the speed change mechanism isadjusted to its first speed stage providing the low-speed drive ratio.One-way brake 38 checks at this stage the carrier 36 in its one runningdirection which corresponds to the direction of the reaction forceinduced in the carrier 36 at the stage of first speed drive, yetallowing it to be free to rotate in the opposite direction. Thus, thecarrier 36 is allowed to rotate in one direction, yet being fixed bysecond brake unit 20, it is capable of receiving in effect twodirectional drive. This is necessary to obtain the desirousengine-braking effect in the L-range.

By virtue of the hydraulic pressure acting upon the differentialpressure receiving area between lands 123aand 123d of the 1-2 positionshaft valve 105, the hydraulic pressure prevailing in the valve chamber194 and that acting upon the differential area between lands 123a and123b, the valve 123 is urged to move upwards in the drawing or towardsthe low speed selecting position and kept in this position, in spite ofthe value of the governor pressure prevailing in the valve chamber 206.

In this case, therefore, the speed change mechanism is kept in the firstspeed or the low speed drive stage, unless the selector lever will havebeen so manipulated that the shift valve 102 is moved form the nowoccupying L-position.

Z-RANGE When the shift valve 102 is moved to 2-position by manipulatingthe selector lever, the valve land 1l4b is brought to a position whereit cooperates with the inwardly projecting ring wall projection 211situated between ports 176 and 177, thus the hitherto establishedhydraulic communication between ports 175 and 177 being therebyinterrupted. Other hydraulic circuit conditions are same as those of theforegoing L-range operation. In effect, the presently establishedhydraulic circuit conditions are such that the hydraulic line pressurehas been released from the conduit 78 and others are same as before. Byvirtue of the failure of line pressure in the said conduit 73, thehitherto acted hydraulic pressure upon the differential area betweenvalve lands 123a and 123d becomes void and the valve will be shifteddownwards or to the vehicle high-speed drive position, should thevehicle speed be increased and the governor pressure prevailing in thevalve chamber 206 increases. In this case, the line pressure in the port201, having been interrupted by valve lands 123a and 123b, will beconveyed from between lands 123b and 123a to port 202, thence throughconduit 81 to the actuating chamber 236 of first brake unit 19. In thisway, it will be clear that at lower vehicle speed, the line pressure isapplied only to first clutch unit 17, other clutch and brake means beingfree from application of the line pressure. By virtue of one-way brake38 brought into actuation, the low speed drive stage is realized. Whenthe vehicle speed increases and the 1-2 position shift valve 105 isshifted to the high speed side, the line pressure is supplied to therespective actuating chambers 231 and 236 of first clutch 17 and firstbrake 19, the second or intermediate speed drive stage will be realized.When the accelerator pedal 34 is suddenly depressed when the vehicle isrunning with the second speed drive stage, the governor pressure will besuddenly decreased by virtue of an abrupt increase of the throttle valvepressure within the port 255 of governor valve 113, thereby the combinedpressure of line pressure prevailing in valve chamber 194 with springforce at 248 overcoming the governor pressure. In this way, the valve123 is moved upwards or to its low speed stage position, the hithertoestablished hydraulic communication between ports 201 and 202 beinginterrupted by valve land 123b. Now, a hydraulic communication betweenports 202 and 203 is established by the valve space defined by valvelands 123b and 1230. Thus, the application of first brake 19 isreleased, while the oneway brake 38 is brought into actuation, therebyestablishing the first speed or low-speed drive stage being brought intorealization. With the vehicle speed increased under these operatingconditions, the governor pressure in valve chamber 206' will increasebeyond the hydraulic pressure urging the valve towards the low-speeddrive position. Then, the valve 123 will be shifted towards thehighspeed drive position, thus the second speed or the intermediatespeed operation being brought about. In this way, with the shift valve102 kept at 2 position, automatic speed change operation will beperformed between the first and second speed drive mode.

D-RANGE When the shift valve 102 is adjusted to D-position bymanipulating the selection lever, the line pressure prevailing inconduit 66 is conveyed through port 174, valve space defined betweenvalve lands [14c and 114d and port 172 to conduit 83, while port 176hitherto kept in fluid communication with port 175 is interrupted byvalve land 1113b, and port 176 is brought into communication withdischarge port 179. Thus, oil pressure is discharged from chamber 194 ofthe l-2 position shift valve 105. With the exception of this, the linepressure is conveyed to same conduits as before where the shift valve102 is kept at the 2-position.

Line pressure is conveyed from conduit 83 to port 220 of the 2-3position shift valve 107. With lower vehicle speed and with the governorpressure being low correspondingly, valve 129 is kept at its upperposition in the drawing under the ac tion of spring 128, thus being keptat the low-speed drive position. The hydraulic line pressure isinterrupted at between the valve lands 12% and 129C. When the vehiclespeed increases under these operating conditions and thus the governorpressure in valve chamber 206 increases correspondingly beyond apredetermined value, it becomes to overcome the spring pressure at 128,acting the valve to urge upwards in the drawing, thus the valve 129being downwards or towards the highspeed drive position. Therefore, linepressure is conveyed from conduit 83 through the port 220, the valvespace defined between valve lands 1290 and 129d, the port 222, theconduit 84 and branch conduits 84a and 84b, to actuating chamber 234 ofsecond clutch 18 and to releasing chamber 239 of first brake 19,respectively. ln this way, the clutch 18 is engaged, while the brake 19is released. By bringing first clutch 17 and second clutch 18 intoactuation, the third or high-speed drive stage can be realized.

When the vehicle is started with the D-position selected out, the speedchange will be performed from the first to the second, thence to thethird speed stage in progression, with corresponding increase of thegovernor pressure in response to the increasing vehicle speed and to theincreasingly opening operation of' the throttle. Or conversely, when thevehicle speed decreases from its highest value, the governor pressurewill decrease correspondingly and the speed change operation is carriedinto effect from the third to the second, and thence to the first speedstage in succession.

These speed change modes can be easily understood by reference to FIGS.5 and 6.

When it is assumed that the vehicle is running with the second speedstage with the shift valve positioned at D-position and the occasionalvehicle speed is less than a certain predetermined value such as 40km/hr, the throttle valve pressure will increase in an abrupt mannerupon sudden depression of accelerator pedal 34 and the governor pressureat 113 will decrease correspondingly abruptly. Thus, under the influenceof spring pressure at 2M, the valve 123 will shift upwards in thedrawing, or towards the low-speed position, thereby the hithertoestablished communication between conduits 72b and 81 being interruptedand the line pressure serving for keeping the first brake 19 in itsapplied position being released through discharge port 203 of valve 105.

In this way, first clutch 17 only is kept in engagement and otherengageable means are kept in ineffective, and in addition to the firstclutch, one-way brake 38 is engaged. in this way, the first or thelow-speed drive stage is brought about.

When further assuming that the vehicle is running at a certain speedbelow a predetermined value such as 80 km/hr and with Ddposition havingbeen selected out, and that the accelerator pedal 34 is depressedsuddenly under these conditions, the governor pressure at 113 isregulated depending upon the throttle pressure which depends in turnupon the degree of depression of accelerator pedal. Then, the valve 129is shifted to the low-speed position under the spring action at 128, forrealizing the second speed change mode. Or alternatively, when thethrottle valve pressure is still higher, while the vehicle speed iscomparatively low, the 2-3 position shift valve 107 is shifted to thelow speed position as before. At the ll-2 position shift valve 105, thespring pressure at 214 overcomes the governor pressure force in thevalve chamber 206 and the valve 123 is shifted to the low-speedposition, thereby the first speed mode being brought about. in this way,rapid down-shift operation either to the second or the first speed modecan be realized, depending upon the more or lesser degree of depressionof the accelerator pedal, on the one hand, and the vehicle running speedoccasionally being realized, on the other hand.

MANUAL DOWN SHIFT With the speed change mechanism so far shown anddescribed, a manual down shift from the high-speed drive ratio may beattained with the selector lever set to D-position, to either theintermediate drive ratio or the low speed drive ratio, by adjusting saidlever to 2- or L-position, respectively. In addition, a manual downshift from the intermediate speed drive ratio with the selector leverset to 2 position, to the low speed drive ratio by shifting the lever toL-position.

When it is desired to make a manual down shift either from D-position or2-position to L-position, specifically selected from the various manualshift possibilities above mentioned, and when the low-speed drive ratiois desired to realize in spite of occasional faster running speed of thevehicle, the desired operation will be checked from its practicalrealization when an excessively high running speed of the engine is noteffectively prevented, because the speed change mechanism will act toprevent the shift to the low-speed drive ratio.

The above specific kind of down shift operation is checked in thefollowing way:

When the selector lever set to D-position or 2-position to provide thehigh or intermediate drive ratio, respectively, is manually shifted downto L-position so as to invite an engine braking condition during vehiclerunning, the governor pressure will generally become higher thanotherwise normal value, because of that in this case the acceleratorpedal has been returned to such position as closing the throttle andthus the throttle valve pressure becomes nearly zero value, thus thelatter pressure providing substantially no effect upon the operation ofadjusting valve 113. With the vehicle speed over a certain predeterminedvalue, the valve-urging governor pressure at 1-2 shift value 105 willovercome the spring pressure 214 and a down shift operation can not berealized. In this case, the shift valve is kept at 2-position. Only whenthe vehicle speed has dropped beyond a certain value, the valve 123 willbe moved upwards in FIG. 2A to the position destined for the low speed,thus the desired low speed drive ratio being realized.

REAR DRIVE By manipulating the selector lever so as to shift the manualshift valve 102 to R-position which means that for rear drive, linepressure will be conveyed to ports 176, 177 and 178. The line pressureconveyed from port 176 the chamber 194 of 1-2 position shift valve 105acts in cooperation with that which is conveyed from port 177 to port205 of the valve 105 upon the valve member 123 for fixingly positioningit at the position destined for the low-speed drive stage. Under theseoperative conditions, line pressure will be conveyed from said port 177through ports 205 and 204 of valve 105 to the actuating chamber 240 ofsecond brake unit 20, thus the latter being brought into engagement. Onthe other hand, the line pressure conveyed from port 178 through conduit79; port 223 of 2-3 position shift valve; the valve" space definedbetween lands 1290 and 129d of valve 129; port 222 and conduits 84, 84aand 84b, to the actuating chamber 234 of second clutch 18, on the onehand, and to the release chamber 239 of first brake unit 19, on theother hand. Thus, the clutch 18 is brought into engagement, while thebrake 19 is released. At this stage, the actuating chamber 231 of firstclutch 17 is kept in fluid communication through conduits 72a and 72;and port 173 of manual shift valve 102, to discharge port 171.Therefore, the first clutch unit is kept in its released position.

By bringing the second clutch and the second brake into engagement inthe above-mentioned way, the rear drive stage is brought about asdesired.

Although, in the foregoing embodiment, the valve 35 is arranged to becontrolled from the foot operated accelerator pedal 34, a slightmodification therefrom can be brought about so as to control the valve35 depending upon the vacuum pressure prevailing in the engine suctionmanifold, not shown. With this modified arrangement, similar effect asmentioned in the foregoing can be attained. For this purpose, aspring-loaded piston cylinder assembly of known construction forproviding a variable mechanical effort depending upon the degree ofvacuum pressure prevailing in the engine suction manifold, is preferablyprovided and the piston is mechanically connected through a mechanicallinkage with said valve 35, although not shown only for simplicity.

From the foregoing, it will be clear that the variable speed mechanismaccording to this invention provides a highly simplified hydrauliccircuit arrangement in comparison with a comparable conventional onewherein the governor pressure and the throttle pressure are applied tothe shift valve means in the opposite sense to each other and thedifferential hydraulic pressure is utilized for performing the speedchange operation, because in the former case the conventional hydrauliccontrol circuit employs a hydraulic circuit between the throttle valveand one or more of the shift valves. in addition, with the'presentinvention it is not absolutely necessary to mount said throttle valve inproximity to the shift'valve means which fact further contributes in thesimplification of the necessary hydraulic circuit arrangement. Thedesign, manufacture and arrangement of the valve bodies can also besimplified and made easier than the conventional hydraulic controldevices We claim:

1. An automatic control means for a vehicle automatic speed changemechanism, said automatic speed change mechanism including a drivingshaft, a driven shaft, a multistage speed change gearing mechanismdrivingly connected between said drive and driven shafts, a plurality ofhydraulically actuated frictionally engageable means operativelyconnected to said speed change gearing mechanism for providing aplurality of speed change ratios between said drive and driven shaftsupon the application of hydraulic pressure thereto, said hydraulicallyactuated frictionally engageable means providing a selected one of saidplurality of speed change ratios, said automatic control meanscomprising, a hydraulic pressure source, hydraulic conduit means forcommunicating the output of said hydraulic pressure source with saidhydraulically actuated frictionally engageable means, hydraulic pressureregulating means in communication with said hydraulic conduit means forregulating the line pressure supplied by said hydraulic pressure source,shift valve means hydraulically connected in said conduit means forselectively controlling the distribution of hydraulic line pressure tosaid hydraulically actuated frictionally engageable means, a throttlecontrol valve communicating with the output of said hydraulic pressuresource for generating a hydraulic pressure in response to an enginethrottle position and load condition, a hydraulic governor valve forgenerating a hydraulic pressure which varies as a function of the speedof said driven shaft, a first hydraulic pressure conduit communicatingthe output of said throttle valve with the input of said governor valve,a

second hydraulic conduit communicating the output of said hydraulicpressure source with the output of said governor valve, said output ofsaid governor valve being further communicated with said shift valvemeans for automatically controlling the operation of said shift valvemeans depending on the speed of said driven shaft, the output of saidgovernor valve being caused to decrease with an increase in the outputpressure of said throttle valve, whereby the shift valve means is causedto down-shift to a lower speed change gear ratio due to the rapiddecrease in the governor valve output pressure.

2. An automatic control means as claimed in claim 1, wherein said secondhydraulic conduit is connected between the line pressure input to saidthrottle valve and the output of said governor valve, and furtherincluding an orifice restriction located in said second conduit, wherebya pressure drop is created between the input to said throttle valve andthe output of said governor valve.

3. An automatic control means as claimed in claim 1, wherein saidgovernor valve means comprises a centrifugally actuated valve meansoperatively connected to said driven shaft, said output pressure of saidthrottle valve acting on said governor valve in opposition to thecentrifugal force thereon, whereby, when said throttle valve isactuated, hydraulic pressure will be supplied to said governor valve inopposition to the centrifugal force thereon to cause the output pressureof said governor valve to be rapidly decreased to down-shift said shiftvalve means to a lower speed change gear ratio.

1. An automatic control means for a vehicle automatic speed changemechanism, said automatic speed change mechanism including a drivingshaft, a driven shaft, a multistage speed change gearing mechanismdrivingly connected between said drive and driven shafts, a plurality ofhydraulically actuated frictionally engageable means operativelyconnected to said speed change gearing mechanism for providing aplurality of speed change ratios between said drive and driven shaftsupon the application of hydraulic pressure thereto, said hydraulicallyactuated frictionally engageable means providing a selected one of saidplurality of speed change ratios, said automatic control meanscomprising, a hydraulic pressure source, hydraulic conduit means forcommunicating the output of said hydraulic pressure source with saidhydraulically actuated frictionally engageable means, hydraulic pressureregulating means in communication with said hydraulic conduit means forregulating the line pressure supplied by said hydraulic pressure source,shift valve means hydraulically connected in said conduit means forselectively controlling the distribution of hydraulic line pressure tosaid hydraulically actuated frictionally engageable means, a throttlecontrol valve communicating with the output of said hydraulic pressuresource for generating a hydraulic pressure in response to an enginethrottle position and load condition, a hydraulic governor valve forgEnerating a hydraulic pressure which varies as a function of the speedof said driven shaft, a first hydraulic pressure conduit communicatingthe output of said throttle valve with the input of said governor valve,a second hydraulic conduit communicating the output of said hydraulicpressure source with the output of said governor valve, said output ofsaid governor valve being further communicated with said shift valvemeans for automatically controlling the operation of said shift valvemeans depending on the speed of said driven shaft, the output of saidgovernor valve being caused to decrease with an increase in the outputpressure of said throttle valve, whereby the shift valve means is causedto downshift to a lower speed change gear ratio due to the rapiddecrease in the governor valve output pressure.
 2. An automatic controlmeans as claimed in claim 1, wherein said second hydraulic conduit isconnected between the line pressure input to said throttle valve and theoutput of said governor valve, and further including an orificerestriction located in said second conduit, whereby a pressure drop iscreated between the input to said throttle valve and the output of saidgovernor valve.
 3. An automatic control means as claimed in claim 1,wherein said governor valve means comprises a centrifugally actuatedvalve means operatively connected to said driven shaft, said outputpressure of said throttle valve acting on said governor valve inopposition to the centrifugal force thereon, whereby, when said throttlevalve is actuated, hydraulic pressure will be supplied to said governorvalve in opposition to the centrifugal force thereon to cause the outputpressure of said governor valve to be rapidly decreased to down-shiftsaid shift valve means to a lower speed change gear ratio.